old chestnut: foreign restaurant

A new restaurant opens near where a group of five friends live.
These friends always eat together and they decide to periodically visit
the new restaurant.

The restaurant serves some sort of foreigncuisine (I've seen the
puzzle written with several different ones) with which none of the
friends are familiar. On their first visit they find that they don't
recognize anything on the menu so they order blindly, each of them
ordering one of the dishes on the menu, not necessarily all distinct.

After this first meal, the friends may be able to identify one or more of
the dishes by its name (for instance, if two people ordered one meal
and the others all ordered different meals, they will know the one they
ordered two of, since they got two plates of it).

After three meals, the friends have tried all the items on the menu, and
they can identify each of them by name. If there was one more item on the
menu, they could not have done this, no matter how they ordered.